Can one remove a specific file from all snapshots?

[Alex Aminoff]

The use case here is that we have data sets of sensitive data that we 
are contractually obligated to delete with no backups at a certain point 
in time. The datasets are stored on a ZFS filesystem (on a truenas from 
IxSystems as it happens). The snapshots are kept for 15 days, so at the 
moment we have to rm the files 15 days before the deadline to be 
compliant. Is there a way to delete a specific file from the live 
filesystem as well as all the snapshots?

I did find a post to this list from 2014:

https://lists.freebsd.org/pipermail/freebsd-fs/2014-October/020307.html

but I don't think it is relevant, and in any case it does not appear 
that the feature that post describes was implemented.

Thanks,

  - Alex Aminoff, NBER